Fetal pulmonary hemodynamics: Doppler reference values in low risk pregnancies

To investigate fetal pulmonary hemodynamics in normal pregnancy using pulsed and color Doppler ultrasonography and to define Doppler reference ranges values in the whole fetal pulmonary circulation during different gestational ages.

A prospective observational study was conducted to evaluate 190 healthy singleton pregnancies between 20 and 38 weeks of gestation, including 10 cases for each gestational age. The main pulmonary artery, right pulmonary artery, left pulmonary artery, ductus arteriosus and pulmonary veins waveforms were evaluated. The waveform profile was studied for each pulmonary vessel investigated. We calculated the normal distribution of data of 12 Doppler parameters, their values were expressed as 5th, 25th, 50th, 75th and 95th centile.

We report several pulmonary hemodynamic changes with the progression of pregnancy. We focused on the hemodynamic values of the parameters most useful in clinical practice and that would better describe the hemodynamic events of this vascular district.

This study reports a complete description of the fetal pulmonary hemodynamics at different gestational ages. Many hemodynamic parameters show a typical change during gestation. The reference ranges described in this study may help in situations where is indicated to evaluate the pulmonary hemodynamics and to identify healthy fetuses from those affected by pathological conditions related mainly to fetal cardiovascular anomalies and/or feto-maternal pathologic conditions.